Improvement in grates for steam-boilers



Nrrnn STATES ATENT A Fries.

JAMES MONTGOMERY, OF BROOKLYN, NEW YORK.

Specification forming part of Letters Patent No. 21,0l3, dated July 27,1858.

To all whom/it may concern,.-

Be itknown that LJAMEs MONTGOMERY, of Brooklyn, in the county of Kings,in the State of New York, have invented certain new and usefulImprovements in Steam-Boilers; andI do hereby declare that, thefollowing is a full, clear, and exact description thereof, referencebeing had to the accompanying drawings, making part of thisspecification, in which- Figure l is a plan, withA a portion of the rearpart in section. Fig. 2 is across vertical section of two connectedboilers, onetaken at the line B B and the other atthe line C C of Fig.l. Fig. 3 is a longitudinal vertical section thereof taken at the line AA of Fig. 2. Fig. 4 is a horizontal section of a modificationexhibitingtwo boilers connected back to back, with one in section to represent theinternal arrangement of the liuc-space; and Fig. 5, a longitudinalvertical section thereof, and Fig. 6 a cross vertical section with onehalf of the width taken at the line C O and the other at the line DD ofFig. 4; and Fig. 7 is a longitudinal section of one of the tubes on anenlarged scale.

The same letters indicate like parts in all the figures. y

In the construction of tubular steam-boilers serious diliculty has beenexperienced in obtaining a sufficient proportional extent of manageablegrate-surface. It is well known that if too thick alayer of coal isplaced on the grate much of the heat will be absorbed in distilling theupper portion of the layerof coal, much of `the combustible matterescaping in the form of carbureted hydrogen Vand carbonio oxide,'theheat evolved from the combustion of the coal nearest the grate effectingthe distillation of carbureted hydrogen from the coal above, while theoxygen of the blast or draft is consumed before it can reach these toinname them, and the carbonio acid produced by the complete combustionof the,-A lower part of the'charge in passing up through the upper parttakes up an additional charge of carbon, thereby forming carbonio oxide,which escapes from the furnace with a large portion of unconsumedcarbon, heat being absorbed instead of being evolved by the change ofcarbonio acid into carbonio oxide. From these well-known facts allexperienced engineers direct the coal to be charged in thin layers asthe only economical mode of management 5 but as steam-boiler furnaceshave been heretofore constructed a sufficient amount of fire cannotbemade because of the limited extent of grate-surface in proportion to thelarge amount of evaporating-surface presented by the tubes and becauseof the supposed impossibility of increasing the amount of fuel withoutthereby inducing the waste from the causes first named. The o'nly way inwhich an increased evolution of heat could be produced would be toenlarge the extent of grate-surface; but no mode of effecting thispractically in large boilers has heretofore been known, becauseif thelength of grate be too great the stoker cannot reach the rear end of thecharge for efficient mauagement, and it is only by an increase of lengththat a greater extent of grate-surface can be obtainedas the utmostwidth has al ready been given. l have, however, succeeded in obtaining amaterial extent of gratesurface in the directionof the length of theboiler to overcome the difficulties above pointed out without theinconveniences above stated; and to this end my invention consists incombining the series of vertical watertubes and the fluc-space among thesaid tubes and communicating with the fire-chamber at one end, ashereinafter described, the extending of the grate along the entirelength of the boiler, or nearly so, with a fire-door at each end,whereby I am enabled to obtain practically the required extent ofgrate-sur face with all the facilities of managing or stoking the lire,while at the lsame time the fire on that parl of the grate nearest thefluespace leading to and among the tubes can be so managed by keepingthereon a thin charge of incandescent coals as to supply through thatportion of the charge the required quantity of highlyheatcd uncombinedoxygen to consume,lhecombustible gases evolved from the charge of coalon the other portion of the grate farthest from the flue-space leadingto and among the water-tubes; the stoking being so arranged as to supplythe fresh charges of coal on the grate farthest from the said line-spaceand the incandescent coals being gradually transferred to the other endof the said grate.

In the accompanying drawings, a represents the outer shell of theboiler, made with parat' lel vertical sides and a semi-cylindrical topand bottom; and b the front and c the back grate, which, if desired, maybe separated by a cross-bridge runningacross the entire give access forthe management of the fireY on the grate in front of the bridge, and theother g to give access to the fire on the grate back of the bridge, sothat the stokers can have ready access to the whole length of thegrate-surface of the largest boilers. Below the grate there is anash-pit h, extending the whole length and breadth of the boiler.

In the boilers represented inFigs. 1, 2, and 3 the products ofcombustion from the ire. chamber pass up in a vertical flue-space fi atone of the rear angles of the boilers, and thence into a horizontalline-space j toward the front, thence turn down around the front edge ofa diaphragm or plate 7c into a returnllue space l, under the saiddiaphragm to the rear end of the boilers, and outinto the stack throughthe other rear angle of the boiler at m. The flue-spacesj and Z are notthe whole width of the boiler, but thereisa water-space a on each sidecommunicating with the water above and below the lines. Numerousvertical water-tubes are placed in the fine-spaces, and extending fromthe top plate of the upper flue to the bottom plate of the lower flue toestablish a free communication between the water above and below the'lues, and by reason of the arrangement of the fines the productsof'combustion in passing up to and along the upper flue circulate amongand around the said tubes, acting on the outside of the upper half oftheir length, and in returning through the lower iiue act in like manneron the lower half of their length, so that the upper part of the lengthof the tubes will be more intensely heated than the lower, thus favoringthe upward circulation of the water through the said tubes, thecirculation of the water being downward .in the water-spaces outside ofthe fines to supply water to the lower ends of the said tubes. l

To prevent the steam generated on the crown-sheet o of the furnace frompassing directly up to the lower end of the tubes, which would have atendency to check the supply of water to that end of the tubes, ashield-plate p is interposed. This plate inclines upward on each sidefrom the middle, and then extends vertically up into the waterways '1ton each side about midway between the side plates of the fines and theoutershell of the boiler, so that all the steam which is generated onthe crown-sheet of the furnace is deiiected laterally on each side andrises between the'vertical parts of this plate and the outer shell ofthe boiler, leaving the other portion of the said water-ways free forthe downward circulation to supply the lower end of the tubes.

The inner division of the vertical fine-space t is double to form awater-leg n', but as the products of combustion in passing over theupper edge thereof to getinto the upper horizontal {ine-Spacey' willimpart a very intense heat to this waterdeg, particularly to the up-VVper edge thereof, which might be injurious,

it' not dangerous. I connect the upper part of this water-leg with' theupper partof Vthe'boiler above the flue-space j by vertical water-tubesj', which afford a free circulation of the water through this water-leg,and thereby protect it against any injurious action of the heat. Thespace between these tubes affords the required space'for the passage ofthe products of combustion.

The water-legs a each side of the furnace are formed each o f two platesconnected together by their lower edge, one riveted to the vertical sideof the boiler and the other to the semi-cylindrical bottom, beingsuitably curved for that purpose, and that part of the` bottom of theboiler which is within the water-legs is cut through with long slots inthe direction of the circumference for the free circulation of waterinto and out of the legs, as indicated by .arrows in Fig. 2.

The shield-plate p may be turned in the middle under the tubes, asrepresented at p', and pierced with holes for the downward passage ofwater and these holes protected by a second shield-plate 0 below, sothat the water from above may passith rough and get below,and at thesame time the steam generated on the crown-sheet will be deiiected andmade to pass up through the side waterlegs n n.

In Fig. 2 there are two boilers represented side by side, the flues ofboth discharging into a common stack q.

The red arrows indicate the direction of the draft.

In Figs. et, 5, and G the boilers are arranged `so that they can beconnected in pairs by their back ends, leaving suflicient space belowthe central stack for stoking the fire on the back grate of both boilersthrough the back fire-doors.

The flue-spaces of each boiler, with their congeries of water-tubes, aredivided into two compartments by a vertical water-way r r. The verticalfine-space i, leading from the tirechamber into the upper horizontalfluesjj, is located at the back end and in the middle of the width ofthe boilers, and there are two flue-spaces m leading to thestack, onefor each iiue,one on each side of the vertical flue t'. The products ofcombustion from the firechamber rise inthe Hue-space t', are separatedby the central water-way r r, and pass horizontally through the two luesj j to the front end, where they pass around the front end of thediaphragm 7c and back in the two lines Z Z to Athe exit-fines m, leadingto the stack. In this construction the central stack, which joins therear end of the two boilers, is constructed separately, so as to t intothe rear end of the two boilers, which mode of construction facilitatesthe transportation of the boilers, as they can be transported separatelyand put up by simply pushing the rear end of each boiler into the casingof the central stack. The bore of the water-tubes s is of equal diameterfrom end to end, as represented in Fig. 7 on an enlarged scale, and theouter surface is also of lequal diameter from the upper end to within afew inches of the lower end, where the diameter is increased, as at t,to increase the thickness of metal for the reason already described.

Inv Figs. il, 5, and 6 the crown-sheet of' the furnace is represented ofa different form, as the boilers may be with any one or all of my saidimprovements, although the best results will be obtained when all of mysaid im provements are used in connection.

The best mode of managing the firesin my improved furnace is to chargethe coal on the front grate, and when it has reached the incandescentstate-that is, after it has been thoroughly coked-to transfer aportionof it in that state into the back grate, leaving a sufficient quantityon the front grate to ignite a fresh charge or" coal, and so on,gradually transferring and charging, which transfer can be readilyeffected by pushing the coals as the combustion proceeds by the stokersin front toward the middle or the fire-bridge, if one be used, and thestokers at the rear drawing the coals onto the back grate. In this way avery intense heat from coked coal will be maintained on the back grate,and as the coals on this back grate have been previously distilled the`blast or draft will supply more oxygen than will be consumed by passingthrough the charge, but which will be intensely heated in so passingthrough the fire, and hence will be in the best condition to iniiame thecombustible gases evolved from the coals on the front grate as they passover theback grate toward the lines. Thus a most perfect combustion ofthe inflammable matter will be effected and in a `manner which will giveout the greatest amount of heat for the coals consu med.

I am aware that boilers have been constructed in the manner of twohorizontal tubular boilers placed back to back with one smoke-box commonto both and with the grates of the two connected so as to appear as onegrate for the two series of flue-tubes and with a door at each end 5 butthis mode of construction does not present the mode of operation which Ihave invented and claim as my invention, for each half of the gratebelongs to and acts in connection with its appropriate set of fine-tubesas in two separate boilers, and the products of combustion from thecoals on one end of the grate cannot be made to pass over the other endof the grate.

Vhat I claim as my invention, and desire to secure by Letters Patent,is-

Combining with a boiler formed with a series of vertical water-tubes,and the flue-s pace k among the said tubes communicating with thetire-chamber at one end only, substantially as described, a grate madethe whole or nearly the whole length of the boiler and with a fire-doorat each end, substantially as and for the purpose specified.

JAMES MON GOMERY Witnesses:

WM. 1I. BISHOP, WM. SELLERS.

